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Factor X (FX) is a vitamin K-dependent enzyme, which acts as an important coagulation factor of coagulation cascade. FX deficiency is an autosomal recessive inherited disease and is often demonstrated in families with consanguity. Pregnancy in women with congenital FX deficiency has been associated with adverse fetal outcomes. We report a case of pregnancy in women with FX deficiency. The patient needed an immediate caesarean section at 38 weeks of gestation because of severe oligohydramnios and fetal distress. FX deficiency during pregnancy was effectively managed, leading to a positive outcome through the optimal utilisation of available resources.

Acquired factor X (FX) deficiency is a rare but well-documented clinical feature of AL amyloidosis. Patients with FX deficiency can present with clinically significant bleeding diathesis due to the adsorption of circulating FX to amyloid fibrils. Here, we report an unusual case of a man in his 60s who presented with 6 months of intermittent bruising, labs demonstrating new FX deficiency, elevated free lambda light chains for underlying AL amyloidosis and concurrent new peroneal vein thrombosis. This is the first report of concurrent thrombotic complications in the setting of AL-amyloid-induced FX deficiency. We discuss the diagnostic and therapeutic conundrum of diagnosing AL amyloidosis with bruising as the leading clinical symptom and the management of acute deep vein thrombosis in the setting of FX deficiency.

UNASSIGNED: Factor X (FX) deficiency is a rare bleeding disorder manifesting a bleeding tendency caused by low FX activity levels. We aim to explore the use of fitusiran (an investigational small interfering RNA that silences antithrombin expression) to increase thrombin generation and the in vivo hemostatic potential under conditions of FX deficiency. We therefore developed a novel model of inducible FX deficiency, generating mice expressing <1% FX activity and antigen (f10low mice). Compared with control f10WT mice, f10low mice had sixfold and fourfold prolonged clotting times in prothrombin time and activated partial prothrombin time assays, respectively (P < .001). Thrombin generation was severely reduced, irrespective of whether tissue factor or factor XIa was used as an initiator. In vivo analysis revealed near-absent thrombus formation in a laser-induced vessel injury model. Furthermore, in 2 distinct bleeding models, f10low mice displayed an increased bleeding tendency compared with f10WT mice. In the tail-clip assay, blood loss was increased from 12 ± 16 μL to 590 ± 335 μL (P < .0001). In the saphenous vein puncture (SVP) model, the number of clots generated was reduced from 19 ± 5 clots every 30 minutes for f10WT mice to 2 ± 2 clots every 30 minutes (P < .0001) for f10low mice. In both models, bleeding was corrected upon infusion of purified FX. Treatment of f10low mice with fitusiran (2 × 10 mg/kg at 1 week interval) resulted in 17 ± 6% residual antithrombin activity and increased thrombin generation (fourfold and twofold to threefold increase in endogenous thrombin potential and thrombin peak, respectively). In the SVP model, the number of clots was increased to 8 ± 6 clots every 30 minutes (P = .0029). Altogether, we demonstrate that reduction in antithrombin levels is associated with improved hemostatic activity under conditions of FX deficiency.

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An elderly woman with light chain myeloma presented with prolonged epistaxis and extensive cutaneous haematomas: her kappa/lambda ratio was high at 395, her coagulation screen, thrombin and reptilase times were abnormal, her FV and FX were in the low range in the absence of specific inhibitors, her Clauss fibrinogen was low at 0.95 g/l but antigenic FNG was 1.58 g/l. The patient denied treatment and died of progressive renal failure. We wish to describe the unusual association of FX and FV deficiency co-existing with an acquired dysfibrinogenaemia.

Hereditary factor X deficiency (HFXD) is a rare bleeding disorder causing delayed haemostasis and potentially life-threatening bleeds. Patient/caregiver burden and diagnosis path have not been well characterized.
UNASSIGNED: describe the diagnosis path, disease burden, and HFXD impact on quality of life (QoL) in patients and caregivers.This was a prospective, cross-sectional, web-based survey of patients with HFXD and caregivers addressing the patient/caregiver experience, QoL, humanistic and unmet needs.Thirty patients and 38 caregivers completed the survey with mean ages 24.7 and 44.6 years, respectively. Mean age at diagnosis was 4.1 years. The diagnostic process was somewhat/very difficult for 23% of patients and 26% of caregivers. Approximately half (53%) received single factor replacement (SFR) as prophylaxis or on-demand. Most patients (71%) reported regular prophylaxis treatment. Over one-fourth (27%) reported treatment with fresh frozen plasma. Bleeding episodes were less common in patients using SFR versus non-SFR: three bleeds or fewer were reported by 92% SFR and 75% non-SFR patients. HFXD patients reported low well being in work/school/social activities with mean HFXD-adapted Hemophilia Well being Index. Patient symptoms negatively impacted caregiver burden with a mean HFXD-adapted Hemophilia Caregiver Index (±SD) of 15.9 (4.6), but also unexpectedly had a positive impact on self-worth and inner strength.To our knowledge, this is the first study to assess patient and caregiver burden of HFXD and impact on QoL. Improvements in symptom recognition, prompt diagnosis, and adherence to expert recommendations for treatment could improve QoL and decrease burden on HFXD patients and caregivers.

BACKGROUND: Hereditary factor X (FX) deficiency (HFXD) is an autosomal recessive rare bleeding disorder that leads to defects in the FX protein. Depending on the degree of deficiency, patients may be at risk of life-threatening bleeding episodes. Historical treatments for FX deficiency include prothrombin complex concentrates, which can increase the risk of thrombosis, and fresh frozen plasma, which can cause volume overload and transfusion reactions. Plasma-derived FX (pdFX), a single-factor, high-purity, high-potency human FX treatment, was approved in 2015 in the United States and in 2016 in Europe for on-demand treatment and prophylaxis of bleeding episodes and perioperative management of patients with HFXD.
METHODS: Five studies that examined the use of pdFX in patients with mild (plasma FX activity [FX:C] ≥5 IU/dL), moderate (FX:C ≥1 and <5 IU/dL), or severe (FX:C < 1 IU/dL) HFXD were reviewed: TEN01, TEN02 and TEN03 were prospective, open-label, multicentre, nonrandomised studies, and TEN05 and TEN06 were multicentre retrospective studies.
RESULTS: When used as an on-demand treatment, pdFX was judged by investigators to be successful in treating 41/42 (97.6%), 2/3 (66.6%) and 79/79 (100%) bleeds in TEN01, TEN02 and TEN05, respectively. When used prophylactically, pdFX was judged \'excellent\' for the prevention of bleeds in nine (100%) and eight (100%) patients in TEN02 and TEN05, respectively. Perioperative treatment and pharmacokinetics were also assessed. pdFX was safe and well tolerated.
CONCLUSIONS: Together, these studies support the use of pdFX for on-demand treatment of bleeding, routine prophylaxis, and perioperative management of bleeding in patients with HFXD.

BACKGROUND: Factor X deficiency is a rare inherited bleeding disorder. To date, 181 variants are reported in the recently updated F10-gene variant database.
OBJECTIVE: This study aimed to describe new F10 variants.
METHODS: The F10 gene was analysed in 16 consecutive families with FX deficiency by a targeted high-throughput sequencing approach, including F10, F9, F8 genes, and 78 genes dedicated to haematological malignancies.
RESULTS: We identified 19 variants (17 missense, one nonsense and one frameshift) and two copy number variations. Two patients presenting a combined FVII-FX deficiency showed a loss of one F10 gene copy (del13q34) associated with a missense variant on the remaining allele, leading to a FX:C significantly lower than the FVII:C level and explaining their unusual bleeding history. We reported five novel variants. Three missense variants (p.Glu22Val affecting the signal peptide cleavage site, p.Cys342Tyr removing the disulphide bond between the FX heavy and light chains, and p.Val385Met located in FX peptidase S1 domain) were detected at compound heterozygosis status in three patients with severe bleeding symptoms and FX:C level below 10 IU/dL. Two truncating variants p.Tyr279* and p.Thr434Aspfs*13 leading to an altered FX protein were found at heterozygous state in two patients with mild bleeding history.
CONCLUSIONS: This study showed the feasibility and the interest of high-throughput sequencing approach for rare bleeding disorders, enabling the report of F10 gene screening in a 3-weeks delay, suitable for clinical use. The description of five new variants may contribute to a better understanding of the phenotype-genotype correlation in FX deficiency.

UNASSIGNED: Multiple myeloma is one of the most common hematologic malignancies. Acquired factor X deficiencies are often observed in primary (AL) amyloidosis and rarely in multiple myeloma.
UNASSIGNED: We report a case of an acquired factor X deficiency in a patient with a newly diagnosed IgA lambda multiple myeloma, without any evidence of concomitant amyloidosis.
UNASSIGNED: We present the patient\'s medical history, clinical and physical examinations, laboratory analysis, and outcome.
UNASSIGNED: A 76-year-old male presented at the emergency department with ongoing gingival bleeding. Several analytical problems with blood sample analysis arose, which eventually led to the diagnosis of a multiple myeloma. Further exploration revealed an acquired factor X deficiency, explaining the ongoing bleeding. There was no evidence of concomitant amyloidosis. The multiple myeloma was treated, leading to complete remission of the malignancy and bleeding tendency.
UNASSIGNED: While coagulopathy is rarely observed in patients diagnosed with multiple myeloma, considering an acquired factor X deficiency becomes relevant when such patient present with bleeding diathesis.